This invention relates to multi-ply braiding machines and, more particularly, to such machines wherein sequenced row and column motion is utilized to eliminate fiber carrier jamming due to tolerance stackups.
The process of braiding is distinguished from weaving in that all fibers are interchanged (moved) in a braiding cycle while in weaving only a single fiber (the fill) is moved through a fixed array of fibers (the warp). Multi-ply braiding is distinguished from conventional braiding in that more than two layers (plys) are formed by the process.
Any braiding process is then characterized by the fact of all fiber carriers being in motion resulting in intertwined fibers. Multi-ply braiding machines use a matrix array of carriers capable of alternate row and column position shifts. Reversal of the direction of row and column motion during a complete shift cycle produces the intertwining of fibers. Production of complex shapes is possible by adjusting the length of travel (number of spaces shifted) of each row or column.
Multi-ply braiding concepts and machines are disclosed in the patents to Bluck No. 3,426,804 and Florentine No. 4,312,261. In the Bluck and Florentine patents, the teachings of which are incorporated herein by reference, each row and column consists of discrete eyelets or carrier blocks. In other machines presently in use, row motion is accomplished by shifting grooved track members containing fiber carriers. Column motion consists of shifting the discrete fiber carriers. In circular concepts, row motion is accomplished by shifting concentric rings or track members. Column (radial) motion again consists of shifting discrete carriers. The present invention pertains to all of the above-mentioned methods (discrete blocks, tracks or rings) as well as other presently known methods of shifting fiber carriers. In the present application, reference to rows and columns are intended to cover braiding concepts wherein the rows and columns are disposed in perpendicular relation, as shown in the drawings, as well as circular arrangements wherein the rows are disposed in concentric relation and the columns are radially disposed.
In all of the braiding concepts considered, row and column motion is accomplished by mechanical, electrical or pneumatic actuators mounted about the perimeter of the apparatus. Accordingly, the motion of an interior fiber carrier is caused by the push from an adjacent carrier or by a shifting of the track beneath. Any misalignment (failure to complete a full shift motion) will prohibit shifting of the perpendicular or transverse rows or columns. Therefore, a failure of any of the large array of moving carriers to achieve a precise position will jam the machine. In an apparatus of practical size this will happen frequently due to the odds of an unfavorable tolerance stack up. The scale of multi-ply braiding equipment is limited, therefore, by the dimensional uniformity which can be achieved in the manufacture of fiber carriers.
In the discrete block or eyelet patents to Bluck and Florentine, this unfavorable stack up can occur in both the row and column directions, although it is most likely to occur in the direction containing the most carriers (long side of the array). An unfavorable stack up will be a random event which occurs when a given row or column contains sufficient undersize or oversize carriers. In the grooved track (or ring) concept an unfavorable stack up is only caused by column (radial) motion and will happen with each column shift. This is because a small gap between tracks (rings) exists and the take up of the accumulated gap when each carrier makes contact and pushes the adjacent carrier results in a misalignment of the carriers nearest the pushing actuator.
The present invention provides the following advantages over presently known braiding concepts and machines:
(1) Eliminates machine jamming;
(2) Permits unjammed operation of multi-ply braiding machines having any number of fiber carriers; and
(3) Permits utilization of lower cost, low tolerance multi-ply braiding machines.